Optimizing the dose of intrathecal morphine in older patients undergoing hip arthroplasty

Determination Of The Efficacy And Side-effect Profile Of Lower Doses Of Intrathecal Morphine In Patients Undergoing Total Knee Arthroplasty

BACKGROUND

Intrathecal (IT) morphine provides excellent post-operative analgesia, but causes multiple side effects including nausea and vomiting (PONV), pruritus and respiratory depression, particularly at higher doses. The lowest effective dose of spinal morphine in patients undergoing total knee arthroplasty is not known.

METHODS

We evaluated the analgesic efficacy and side effect profile of 100 - 300 μg IT morphine in patients undergoing elective total knee replacement in this prospective, randomized, controlled, double-blind study. Sixty patients over the age of 60 undergoing elective knee arthroplasty were enrolled. Patients were randomized to receive spinal anaesthesia with 15 mg Bupivacaine and IT morphine in three groups: (i) 100 μg; (ii) 200 μg; and (iii) 300 μg.

RESULTS

Both 200 μg and 300 μg IT morphine provided comparable levels of postoperative analgesia. However, patients that received 100 μg had greater pain postoperatively, with higher pain scores and a greater requirement for supplemental morphine. There were no differences between groups with regard to PONV, pruritus, sedation, respiratory depression or urinary retention.

CONCLUSION

Both 200 μg and 300 μg provided comparable postoperative analgesia, which was superior to that provided by 100 mug IT morphine in patients undergoing total knee arthroplasty. Based on these findings, we recommend that 200 μg IT morphine be used in these patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT00695045.

Comparison of high- and low-dose intrathecal morphine for spinal fusion in children

BACKGROUND

The purpose of this prospective study was to assess the blood-sparing effect, the quality of analgesia, and the incidence of side-effects of a low-dose regime of intrathecal opioids (ITO) when compared with those of a high-dose regime in scoliosis surgery in children.

METHODS

Forty-six children were randomly included into one of the three groups to receive morphine 5 microg kg(-1) plus sufentanil 1 microg kg(-1) [low-dose intrathecal opioid (LITO)], morphine 15 microg kg(-1) plus sufentanil 1 microg kg(-1) [high-dose intrathecal opioid (HITO)] intrathecally, or no intrathecal opioid. Postoperative analgesia was provided by i.v. opioids. Intraoperative blood loss, postoperative quality of analgesia, opioid requirements, and the incidence of side-effects were recorded for 3 days.

RESULTS

Intraoperative blood loss was significantly reduced by ITOs [LITO: 41.4 (sd 18.8) ml kg(-1); HITO: 37.5 (6.9) ml kg(-1); control: 76.9 (15.3) ml kg(-1), P<0.001], with no difference between the two intrathecal opioid groups. Mean pain scores on the day of surgery were lower in both intrathecal opioid groups (LITO: 2.2 and HITO: 2.1) when compared with the control group (4.1, P<0.03) and opioid consumption was significantly decreased [LITO: 304.3 (65.0) microg kg(-1); HITO: 224.1 (51.8) microg kg(-1); control: 667.7 (89.5) microg kg(-1), P<0.002]. Side-effects of intrathecally administered opioids were similarly frequent in all groups.

CONCLUSIONS

Intrathecal administration of opioids significantly reduces blood loss and postoperative opioid demand, thereby showing side-effects comparable with the control group. These effects were already seen with the low-dose regimen and high dose did not further improve efficacy.

The elderly patient and postoperative pain treatment

The management of postoperative pain in elderly patients can be a difficult task. Older patients have co-existing diseases and concurrent medications, diminished functional status and physiological reserve and age-related pharmacodynamic and pharmacokinetic changes. Pain assessment presents numerous problems arising from differences in reporting cognitive impairment and difficulties in measurement. The elderly are also at higher risk of adverse consequences from surgery and unrelieved or undertreated pain. Selection of analgesic therapy needs to balance the potential efficacy with the incidence of interactions, complications or side effects in the post-operative period. Drug titration in the post-anaesthesia care unit should be encouraged together with analgesia on request in the wards. Multimodal analgesia, using acetaminophen, non-steroidal anti-inflammatory drugs or other non opioid drugs, is the best way to decrease opioid consumption and thus opioid-related adverse events. Sophisticated analgesic methods like PCA, regional analgesia and PCEA are not contraindicated in the elderly but pain relief and side effects should be monitored.

The frequency and timing of respiratory depression in 1524 postoperative patients treated with systemic or neuraxial morphine

STUDY OBJECTIVE

To describe the frequency and timing of intravenous patient-controlled analgesia (IV-PCA) or neuraxial morphine-induced postoperative respiratory depression.

DESIGN

Audit of data captured by routine quality assurance of the acute pain protocols that were implemented by nurses performing routine postoperative care.

SETTING

The surgical wards of a university-affiliated, 700-bed, tertiary hospital.

PATIENTS AND INTERVENTIONS

In real time, the data of all patients enrolled into our Acute Pain Service (APS) were entered and stored in the APS database. Thereafter, patients who had received IV morphine via a PCA device or neuraxial morphine between January 1999 and December 2002 were isolated. From this subset, all patients in whom a respiratory rate (RR) less than 10 breaths per minute was recorded were retrieved.

MEASUREMENTS AND MAIN RESULTS

From a total of 4500 patients, IV or neuraxial morphine was administered to 1524 patients. Eighteen (1.2%) cases of an RR less than 10 breaths per minute were recorded (13 patients, 4 patients, and 1 patient in the IV-PCA, daily epidural morphine, and single-dose intrathecal morphine groups, respectively). A direct correlation between intraoperative fentanyl administration and postoperative respiratory depression was demonstrated between the IV-PCA (P = 0.03) and epidural groups (P = 0.05). The time from IV-PCA initiation or last neuraxial morphine administration until the diagnosis of respiratory depression ranged between 2 hours and 31.26 hours and 2 hours and 12.15 hours, respectively. Ten (55.6%) patients received naloxone.

CONCLUSION

Morphine-induced respiratory depression may occur at any time during the APS admission. However, the optimal frequency of intermittent RR monitoring is unknown. Furthermore, because multiple variables (age, sex, prior opioid administration, site of operation) may affect morphine-induced respiratory depression, further investigation must be performed to determine the ideal monitoring protocol.

A procedure-specific systematic review and consensus recommendations for analgesia after total hip replacement

Total hip replacement is a major surgical procedure usually associated with significant pain in the early postoperative period. Several anaesthetic and analgesic techniques are in common clinical use for this procedure but, to date, clinical studies of pain after total hip replacement have not been systematically assessed. Using the Cochrane protocol, we have conducted a systematic review of analgesic, anaesthetic and surgical interventions affecting postoperative pain after total hip replacement. In addition to the review, transferable evidence from other relevant procedures and clinical practice observations collated by the Delphi method were used to develop evidence-based recommendations for the treatment of postoperative pain. For primary total hip replacement, PROSPECT recommends either general anaesthesia combined with a peripheral nerve block that is continued after surgery or an intrathecal (spinal) injection of local anaesthetic and opioid. The primary analgesic technique should be combined with a step-down approach using paracetamol plus conventional non-steroidal anti-inflammatory drugs, with strong or weak opioids as required.

Improved analgesia with clonidine when added to local anesthetic during combined spinal-epidural anesthesia for hip arthroplasty: a double-blind, randomized and placebo-controlled study

BACKGROUND

The perioperative effects of intrathecal and epidural clonidine combined with local anesthetic were evaluated in 60 patients undergoing hip arthroplasty.

METHODS

This was a double-blinded study and the patients were randomized into three groups, with 20 patients in each group. All patients received spinal anesthesia with 17.5 mg of plain bupivacaine with 15 microg of clonidine (Group BC-RC) or without clonidine (Groups B-R and B-RC). Postoperatively, epidural infusion was administered in the following way: Group B-R-ropivacaine 4 mg h(-1); Groups B-RC and BC-RC: ropivacaine 4 mg h(-1) and clonidine 40 microg h(-1). Sensory block was assessed with light touch, pinprick, transcutaneous electrical stimulation at T12 and L2 dermatomes, and perception of thermal stimuli.

RESULTS

The maximal upper level of sensory block measured by pin-prick (T6-T7) did not differ between the groups while the partial sensory block for cold and warmth were increased two dermatomes above pin-prick level in the group with intrathecal clonidine compared to the other two groups (P < 0.05). Duration of anesthesia, analgesia and motor block were longer in Group BC-RC compared to Groups B-R and B-RC (P < 0.02). Postoperatively, both VAS score on movement and PCA-morphine consumption were higher in Group B-R than in Groups B-RC and BC-RC (P < 0.01). The arterial pressure and heart rate in Groups B-RC and BC-RC were significantly lower than in Group B-R at 10-24 and 15-24 h, respectively, after spinal injection.

CONCLUSION

Low-dose intrathecal clonidine provided a better quality of anesthesia and longer-lasting analgesia. Epidural clonidine-ropivacaine infusion resulted in improved postoperative analgesia but was associated with a moderate decrease in blood pressure.

Endogenous opiates and behavior: 2003

This paper is the 26th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2003 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).